The present invention relates to a controlled release formulation of bupropion hydrochloride. The compound bupropion hydrochloride is described in U.S. Pat. No. 3,819,706 as an antidepressant.
U.S. Pat. No. 5,427,798 describes a controlled release formulation of bupropion which based on a ratio of hydroxypropyl methylcellulose which is 1 part of bupropion to 0.19 to 1.1 parts of hydroxypropyl methylcellulose. U.S. Pat. No. 5,358,970 discloses a formulation of bupropion hydrochloride which is stabilized with a stabilizer which has specific acid properties under particular test conditions. RE 33,994 is limited to a bupropion hydrochloride controlled release formulation which releases 10-45% of bupropion hydrochloride within two hours; 25-70% bupropion hydrochloride within 4 hours and 40-90% of bupropion hydrochloride within six hours. Wellbutrin SR is a commercially available twice a day dosage form of bupropion hydrochloride which contains carnauba wax, cysteine hydrochloride, hydroxypropyl methylcellulose, magnesium stearate, microcrystalline cellulose, polyethylene glycol and titanium dioxide.
The applicants have discovered that a two pellet controlled release formulation may be employed to provide a dosage formulation which has a controlled release profile which is bioequivalent to Wellbutrin SR but has a distinctly different in vitro release profile than Wellbutrin SR.